The LaFeO perovskite oxide has been proved to be an effective catalyst in the gas nitriding. However, its catalytic efficiency was sensitive to the nitriding parameters. In order to clarify the catalytic conditions of the LaFeO oxide, the low-pressure gas nitriding was carried out in the present work. The effects of gas pressure and ammonia flow rate on catalytic behavior of the LaFeO oxide were discussed. The catalytic feature and conditions of the LaFeO oxide was identified. The microstructure and phase composition of nitrided layers were analyzed by the optical microscope, transmission electron microscopy, scanning electron microscope and X-ray diffraction, respectively. The microhardness profiles of nitrided layers were measured by micro-hardness tester to evaluate catalytic efficiency of the LaFeO oxide. The X-ray photoelectron spectroscopy was applied to reveal the catalytic behavior. The results show that the LaFeO perovskite oxide exhibited an excellent catalytic activity via accelerating dissociation of ammonia molecules and diffusion of nitrogen atoms. The dehydrogenation reaction of ammonia molecules was the rate-determining step for the rare earth nitriding, which was greatly affected by gas pressure and ammonia flow rate. The LaFeO catalyst shows an excellent durability of catalytic activity in low pressure and low flow rate conditions.

中文翻译：

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LaFeO3钙钛矿氧化物在低压气体氮化过程中的催化行为


LaFeO钙钛矿氧化物已被证明是气体氮化的有效催化剂。然而，其催化效率对氮化参数敏感。为了阐明LaFeO氧化物的催化条件，本工作进行了低压气体氮化。讨论了气体压力和氨流量对LaFeO氧化物催化行为的影响。确定了 LaFeO 氧化物的催化特征和条件。分别通过光学显微镜、透射电子显微镜、扫描电子显微镜和X射线衍射分析了渗氮层的显微组织和物相组成。通过显微硬度测试仪测量氮化层的显微硬度分布，以评估LaFeO氧化物的催化效率。 X射线光电子能谱被用来揭示催化行为。结果表明，LaFeO钙钛矿氧化物通过加速氨分子的解离和氮原子的扩散而表现出优异的催化活性。氨分子的脱氢反应是稀土渗氮的决定步骤，受气体压力和氨流量的影响较大。 LaFeO催化剂在低压和低流量条件下表现出优异的催化活性耐久性。